The present invention relates to ball transfer units utilized to provide a conveying surface on which articles may be readily moved.
Ball transfer units are widely employed in connection with conveyors for movement of various articles such as cargo from an aircraft. The ball transfer units are assembled in a housing or support to provide a surface containing many spherical balls upon which the articles are readily moved. Illustrative of such ball transfer units are Coelln U.S. Pat. No. 5,540,314, Barnes et al U.S. Pat. No. 5,516,211 and Huber U.S. Pat. No. 5,033,601.
Generally, such ball transfer units comprise a housing providing a well in which a large conveyor ball is seated and the conveyor ball rides upon small ball bearings which in turn roll upon the surface of the well. Many units include caps to provide some sealing action at the upper portion of the well so as to limit debris from falling into the well and interfering with the operation of the transfer unit. To avoid accumulation of debris and water within the well, it is customary to provide a through passage at the bottom of well.
Conventionally, the centers of the conveyor ball and of the arc which defines the arcuate surface of the well are coincident so that the spacing between the conveyor ball and the surface of the well is uniform at least over the lower portion thereof. As a result, most of the load on the conveyor ball is transferred to the housing adjacent the bottom of the well, and this is generally the weakest section for the housing.
It is an object of the present invention to provide a novel ball transfer unit in which the load is transferred from the conveyor ball to the housing in an area where the housing is of greater strength than at its base.
It is also an object to provide such a ball transfer unit which may be fabricated readily and which provides enhanced durability.
Another object is to provide such a ball transfer unit which is relatively economical to fabricate and to assemble.